Connection channel freezing method construction simulation test device

Abstract

The invention discloses a communication channel freezing method construction simulation test device which comprises a test box body, a sensor assembly and a freezing pipe, a test soil body is placed in the test box body, the sensor assembly is arranged in the test box body, the freezing pipe transversely penetrates through the test box body, and a cooling agent circularly circulates in the freezing pipe. The test box body is provided with two test excavation openings which are symmetrically arranged on the test box body, a transverse area formed between the two test excavation openings is an excavation area, and the freezing pipe is arranged around the excavation area. The temperature sensor and the displacement sensor are arranged in the test box body, surface soil settlement, deep soil displacement and the temperature of different positions of the soil in the whole experiment period can be comprehensively monitored, two symmetrical test excavation openings are formed in the test box body, the freezing pipe is arranged on the periphery of the excavation area, and the freezing pipe is arranged in the test box body. The actual environment of contact channel freezing method construction can be simulated more truly, and a scientific basis is provided for construction control.

Description

Technical Field

[0001] This invention belongs to the field of simulation test technology, and specifically relates to a simulation test device for the construction of a connecting passage using the freezing method. Background Technology

[0002] As urban underground space development extends to areas with complex geological conditions, the freezing method, as a key technology for controlling groundwater and reinforcing weak strata in tunnel engineering, has been widely applied in scenarios such as aquifer crossings and connecting passage construction. This method forms a frozen curtain through artificial cooling, effectively improving the mechanical properties of the strata. However, its construction process involves complex multi-field coupling of heat, force, and water, and issues such as frost heave effect, temperature field evolution law, and thaw settlement control directly affect the safety of the project.

[0003] Existing simulation studies for the construction of frozen connection tunnels mainly employ a combination of numerical simulation and physical model testing. In terms of numerical simulation, although software such as ANSYS and COMSOL can perform multi-field coupled calculations, limitations such as constitutive model simplification and idealized boundary conditions make it difficult to accurately characterize the nonlinear characteristics of the frozen soil phase change process. Regarding physical model testing, the invention patent for a horizontal frozen soil frost heave and thaw settlement stress simulation device (application publication number CN109374463) places pressure sensors in the soil to monitor pressure changes during frost heave and thaw settlement. However, during construction, it mainly uses the displacement of the soil surface and surrounding areas as a reference, thus this scheme cannot fully obtain the thaw settlement law. The invention patent for a frost heave and thaw settlement test device (application publication number CN113607919) obtains the thaw settlement and frost heave amounts through pressure sensor data around the soil and a processor, but it cannot obtain the displacement of various points on the soil surface and deep soil layers during frozen soil tunnel excavation, thus it cannot effectively guide construction. Summary of the Invention

[0004] The purpose of this invention is to solve the aforementioned technical problems in the prior art and to provide a simulation test device for the construction of a connecting passage using the freezing method. By setting temperature and displacement sensors inside the test chamber, it is possible to comprehensively monitor the surface soil settlement, deep soil displacement, and temperature at different locations of the soil throughout the entire experimental cycle. The test chamber is equipped with two symmetrical test excavation openings, and the freezing pipes are placed around the excavation area, which can more realistically simulate the actual environment of the construction of the connecting passage using the freezing method and provide a scientific basis for construction control.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A simulation test device for the construction of a connecting passage using the freezing method includes a test chamber, a sensor assembly, and a freezing pipe. The test chamber contains test soil, and the sensor assembly, including a temperature sensor and a displacement sensor, is located inside the test chamber. The freezing pipe runs horizontally through the test chamber, and coolant circulates within it. Two test excavation openings are provided on the test chamber, located on opposite horizontal sides of the test chamber and symmetrically arranged. The horizontal area formed between the two test excavation openings is the excavation area, and the freezing pipe is located around the excavation area.

[0006] Furthermore, liquid nitrogen is used as the coolant.

[0007] Furthermore, it also includes a fixed support, with the test chamber housed within the fixed support.

[0008] Furthermore, the fixing bracket is composed of welded angle steel.

[0009] Furthermore, a window cover was installed at the test excavation opening.

[0010] Furthermore, the temperature sensors are evenly distributed in an array along the axis perpendicular to the excavation area, and the temperature sensors are positioned away from the excavation area.

[0011] Furthermore, each freezing tube is equipped with a temperature sensor.

[0012] Furthermore, the displacement sensor includes a deep soil displacement sensor and a surface soil displacement sensor. The deep soil displacement sensor is inserted longitudinally into the test soil, and the surface soil displacement sensor is inserted into the top surface of the test soil.

[0013] Furthermore, the deep soil displacement sensors are arranged at intervals along the axis parallel to the excavation area, and at equal intervals along the axis perpendicular to the excavation area.

[0014] Furthermore, the surface soil displacement sensors are arranged at intervals along the axis parallel to the excavation area, and one of the surface soil displacement sensors is located directly above the axis of the excavation area.

[0015] The present invention, by adopting the above-described technical solution, has the following beneficial effects: This invention, by installing temperature and displacement sensors within the test chamber, comprehensively monitors surface soil settlement, deep soil displacement, and soil temperature at different locations throughout the entire experimental cycle. The test chamber features two symmetrical excavation openings, with freezing pipes positioned around the excavation area, enabling a more realistic simulation of the actual environment during the construction of the connecting tunnel using the freezing method, providing a scientific basis for construction control. The gridded and arrayed sensor arrangement in this application accurately captures uneven settlement, horizontal displacement, and deep soil deformation, providing high-precision data support for the study of frost heave and thaw settlement mechanisms. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram showing the positional distribution of the temperature sensors within the test chamber in this invention; Figure 2 This is a schematic diagram of the arrangement of the cryogenic tubes within the test chamber in this invention; Figure 3 This is a schematic diagram of the layout of the surface soil displacement sensor inside the test chamber in this invention; Figure 4 This is a schematic diagram showing the positional distribution of the deep soil displacement sensor within the test chamber in this invention. Figure 5 This is a schematic diagram of the internal structure of a simulation test device for the construction of a connecting passage using the freezing method.

[0017] In the figure, 1-test chamber; 2-test soil; 3-freezing pipe; 4-test excavation opening; 5-excavation area; 6-fixed bracket; 7-window cover; 8-temperature sensor; 9-deep soil displacement sensor; 10-surface soil displacement sensor. Detailed Implementation

[0018] like Figures 1 to 5As shown, this invention provides a simulation test device for the freezing method of a connecting passage construction. It includes a test chamber 1, a sensor assembly, and a freezing pipe 3. Test soil 2 is placed inside the test chamber 1 to simulate the soil during actual excavation. The sensor assembly, located inside the test chamber 1, includes a temperature sensor 8 and a displacement sensor. The freezing pipe 3 runs horizontally through the test chamber 1, circulating coolant within it. Two test excavation openings 4 are provided on the test chamber 1, located on opposite horizontal sides and symmetrically arranged. The horizontal area formed between the two excavation openings 4 is the excavation area 5, simulating the bidirectional excavation process of a connecting passage, thus more closely resembling the actual engineering scenario. A window cover 7 is provided at each test excavation opening 4. The window cover 7 can close the excavation opening during the non-excavation stage, reducing soil moisture evaporation and temperature fluctuations, maintaining the stability of the initial soil state, and then quickly opening it again during excavation to simulate construction.

[0019] The test chamber 1 in this application is preferably designed as a hollow cuboid structure with a square internal cavity and an open top. The test chamber 1 has a certain thickness to ensure the overall structural stability and reliability. The device also includes a fixed support 6, within which the test chamber 1 is housed. The fixed support 6 is assembled from angle steel welded together. The fixed support 6 further constrains and stabilizes the test chamber 1. In the actual design, the fixed support 6 provides limiting support to the four sides of the test chamber 1, effectively improving the overall structural robustness and preventing deformation or displacement of the test chamber 1 during the experiment, thus ensuring the stability and accuracy of the experiment. The use of angle steel welded together to assemble the fixed support 6 ensures the overall structural strength and rigidity of the fixed support 6, guaranteeing its stability and durability, and also facilitating actual processing and assembly.

[0020] The freezing tube 3 is located inside the test chamber 1, with both ends of the freezing tube 3 penetrating the chamber. The freezing tube 3 is positioned around the excavation area 5, parallel to the excavation direction during the test. Liquid nitrogen is used as the coolant in the freezing tube 3. One end of the freezing tube 3 is the liquid inlet, and the other end is the liquid outlet, facilitating the circulation of the refrigerant. Using liquid nitrogen as the refrigerant is advantageous because liquid nitrogen has an extremely low boiling point and extremely high cooling efficiency, which can rapidly reduce the soil temperature, significantly shorten the formation time of the freezing curtain, improve test efficiency, and ensure uniform heat absorption during the phase change of liquid nitrogen, which is conducive to forming a stable and controllable temperature field, and more realistically simulates and reflects the temperature gradient and phase change behavior during the freezing process.

[0021] Temperature sensors 8 are evenly distributed in an array along an axis perpendicular to the excavation area 5, and are positioned away from the excavation area 5. Each freezing tube 3 is equipped with a temperature sensor 8. This array arrangement of temperature sensors 8 comprehensively captures the spatial distribution characteristics of the soil temperature field, avoiding monitoring blind spots. The design of avoiding the excavation area 5 prevents the temperature sensors 8 from being damaged during excavation. Simultaneously, it focuses on monitoring the temperature gradient changes during the formation and evolution of the freezing curtain, providing detailed data support for analyzing the frost heave and thaw settlement mechanism. In actual design, with the array distribution, each freezing tube 3 is also equipped with a temperature sensor 8 to directly monitor the surface temperature of the freezing tube 3. This allows for real-time monitoring of the refrigerant's cooling effect and the operating status of the freezing tube, facilitating the adjustment of liquid nitrogen flow rate and freezing speed, ensuring the uniformity and stability of the freezing curtain, and improving the controllability and accuracy of the experiment. The temperature sensors are constantan thermocouples, which have good low-temperature measurement stability and accuracy, suitable for low-temperature environment monitoring in freezing method experiments.

[0022] The displacement sensors include a deep soil displacement sensor 9 and a surface soil displacement sensor 10. The deep soil displacement sensor 9 is inserted longitudinally into the test soil mass 2, while the surface soil displacement sensor 10 is inserted into the top surface of the test soil mass 2. These two types of displacement sensors monitor the displacement changes of the surface and deep soil masses respectively, comprehensively reflecting the deformation characteristics of the soil at different depths during frost heave and thaw settlement, revealing the causes and distribution patterns of uneven settlement, and providing more comprehensive displacement data support for engineering practice. The deep soil displacement sensor 9 is a fiber Bragg grating sensor. Fiber Bragg grating sensors have the advantages of anti-interference and the ability to perform distributed measurement in series, making them very suitable for long-term, accurate deep deformation monitoring buried in soil. When deployed in key areas, they can accurately capture the internal deformation of soil at different depths. The surface soil displacement sensor 10 is a displacement gauge, which is suitable for monitoring settlement on the soil surface.

[0023] The deep soil displacement sensors 9 are arranged at intervals along the axis parallel to the excavation area 5, and also at equal intervals along the axis perpendicular to the excavation area 5. This arrangement can accurately capture the displacement field distribution of deep soil in three-dimensional space, and is especially capable of monitoring the mechanical response of the soil around the frozen curtain, providing high-resolution data for analyzing the stability of the frozen wall and the soil deformation mechanism.

[0024] The surface soil displacement sensors 10 are arranged at intervals along an axis parallel to the excavation area 5, with one row of surface soil displacement sensors 10 positioned directly above the axis of the excavation area 5. The sensors primarily monitor the maximum value of surface settlement and the morphology of settlement troughs near the excavation axis. Combined with the symmetrically arranged sensors on both sides, the lateral distribution pattern of surface settlement can be comprehensively characterized, providing crucial data for assessing the impact of excavation on the surface.

[0025] This invention, by installing temperature sensors 8 and displacement sensors inside the test chamber 1, can comprehensively monitor surface soil settlement, deep soil displacement, and soil temperature at different locations throughout the entire experimental cycle. The test chamber 1 has two symmetrical excavation openings 4, and freezing pipes 3 are located around the excavation area 5, which can more realistically simulate the actual environment of the freezing method construction of the connecting tunnel, providing a scientific basis for construction control. The gridded and arrayed arrangement of sensors in this application can accurately capture uneven settlement, horizontal displacement, and deep soil deformation, providing high-precision data support for the study of frost heave and thaw settlement mechanisms.

[0026] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A simulation test device for the construction of a connecting passage using the freezing method. Its features are, include: A test chamber containing test soil; A sensor assembly, which is disposed inside the test chamber, includes a temperature sensor and a displacement sensor. A freezing tube, which extends laterally through the test chamber, and a coolant flows through the freezing tube; The test chamber is provided with two test excavation openings, which are respectively located on two horizontally opposite sides of the test chamber and are symmetrically arranged on the test chamber. The transverse area formed between the two test excavations is the excavation area, and the refrigeration pipe is located around the excavation area.

2. The simulation test device for the construction of a connecting passage using the freezing method according to claim 1, characterized in that: The coolant used is liquid nitrogen.

3. The simulation test device for the construction of a connecting passage using the freezing method according to claim 1, characterized in that: It also includes a fixed bracket, and the test chamber is located inside the fixed bracket.

4. The simulation test device for the construction of a connecting passage using the freezing method according to claim 3, characterized in that: The fixed bracket is made of angle steel welded together.

5. The simulation test device for the construction of a connecting passage using the freezing method according to claim 1, characterized in that: A window cover was installed at the test excavation opening.

6. The simulation test device for the construction of a connecting passage using the freezing method according to claim 1, characterized in that: The temperature sensors are evenly distributed in an array along an axis perpendicular to the excavation area, and the temperature sensors are positioned away from the excavation area.

7. The simulation test device for the construction of a connecting passage using the freezing method according to claim 6, characterized in that: Each of the aforementioned refrigeration tubes is equipped with a temperature sensor.

8. The simulation test device for the construction of a connecting passage using the freezing method according to claim 1, characterized in that: The displacement sensor includes a deep soil displacement sensor and a surface soil displacement sensor. The deep soil displacement sensor is inserted longitudinally into the test soil, and the surface soil displacement sensor is inserted into the top surface of the test soil.

9. The simulation test device for the construction of a connecting passage using the freezing method according to claim 8, characterized in that: The deep soil displacement sensors are arranged at intervals along the axis parallel to the excavation area, and are also arranged at equal intervals along the axis perpendicular to the excavation area.

10. The simulation test device for the construction of a connecting passage using the freezing method according to claim 8, characterized in that: The surface soil displacement sensors are arranged at intervals along an axis parallel to the excavation area, with one row of surface soil displacement sensors positioned directly above the axis of the excavation area.

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